Such fuel injection valves are described in German Patent No. 30 00 061 and British Patent No. 759 524. German Patent No. 30 00 061 describes the use of a heat shield sleeve on the nozzle body of the fuel injection valve. A flange of the heat shield sleeve is inserted into an inside groove in the fuel injection valve and sealed by a sealing ring with respect to the receiving bore of the cylinder head. On the spray side, the heat shield sleeve has a ring-shaped collar that is bent inward, with an elastic heat shield ring supported on the collar. The heat shield ring is arranged between the spray end of the nozzle body of the fuel injection valve and the ring-shaped collar of the heat shield sleeve that is bent inward.
With the fuel injection nozzle described in British Patent No. 759 524, a flexible heat shield element inserted between an end face of the nozzle body and a collar of a clamping nut is designed as a disk-shaped heat shield ring made of a thermal insulation material. To protect the inside of the heat shield ring, which is not covered by the collar or the nozzle body, from attack by combustion gases, the inside is bordered by a U-shaped ring of thin sheet metal.
A disadvantage of these conventional fuel injection valves is that the thermal coupling between the nozzle body and the cylinder head is not entirely satisfactory because the radial pressure is limited due to the maximum allowed assembly forces. Therefore, there is the risk of overheating the nozzle body and coking during operation of the internal combustion engine.